# API documentation

> OpenAI-compatible API documentation for the Free AI Gateway.

Canonical: https://ai-gateway.sassmaker.com/docs/

An OpenAI-compatible gateway across free-tier providers. Start with [`/docs/getting-started`](https://ai-gateway.sassmaker.com/docs/getting-started/) or jump directly to an API reference below.

## [Getting started](https://ai-gateway.sassmaker.com/docs/getting-started/)

Connect an OpenAI-compatible client to the gateway.

## [Chat completions](https://ai-gateway.sassmaker.com/docs/chat-completions/)

Generate text with streaming, tools, JSON mode, and vision.

## [Responses API](https://ai-gateway.sassmaker.com/docs/responses-api/)

Use the OpenAI Responses format through the gateway.

## [Decision APIs](https://ai-gateway.sassmaker.com/docs/decisions/)

Answer typed questions and compare engines on one frozen input.

## [Models](https://ai-gateway.sassmaker.com/docs/models/)

Browse routing capabilities and available model families.

## [Authentication](https://ai-gateway.sassmaker.com/docs/authentication/)

Authenticate protected requests with a gateway key.

OpenAI-compatible endpoints live under `/v1`.